The present invention concerns an operating circuit for discharge lamps, particularly low-pressure discharge lamps. Here and in the following as well as in the claims, operating circuits for several lamps are also intended, i.e., operating circuits for at least one lamp. Discharge lamps are operated with alternating-current power, usually with a high-frequency power. A coupling capacitor connected in series with the lamp is used for direct-current coupling. Refer to C. H. Sturm and E. Klein "Operating devices and circuits for electrical lamps", 6th Edition 1992, Siemens AG, with respect to the basic structure of such operating circuits.
During ignition and operation of a discharge lamp, different interference states may occur, which can lead to the disruption of the operating circuit and result in safety risks relative to the environment. Therefore, a circuit structure is aimed at, which automatically detects such disruptive states and leads to a disconnection of the lamp.
Circuits with safety disconnection devices are known, which respond to the lamp voltage, thus the voltage released at the discharge segment of the lamp. The invention correspondingly proceeds from a circuit for alternating-current voltage operation of a discharge lamp by means of a coupling capacitor connected in series with the lamp for direct-current separation with a safety disconnection device, as is known for the OSRAM QTEC ballast device.